"There are times where it's like, 'I'd rather not have to go through any of this,' and my desire is that I would be freed from, really, this metaphorical cage," said Shannon.

Shannon decided he wasn’t going to let the disease define him.

"Obviously, my physical ability is limited in great ways, but my ability to use my mind and love others is not limited," he said.

He wrote a book that includes letters written to family members, doctors, friends and every person who has touched his life.

When Shannon received letters back, he was surprised to learn that people didn’t see him as a kid who lost the use of his legs.

Instead, they saw a young man with unwavering faith and perseverance.

"Someone who did not let a moment go to waste," he said. "Someone who lived with excellence with what they had, and really lived as if the sky was the limit, and even when there were limitations, rose above them."